Tyre fitter took the loose lacquer back, re-lacquered (only the edge of the rim I assume), and used rubber solution, at least that's what he told me. I've had no issues since, but the wheel looks a mess now. Annoying really, considering the wheels are less than 2 years old, having been replaced under warranty. I'm somewhat tempted to contact Mazda to see if they'll replace again (although I'm now 8 months out of warranty)